Chemical and structural studies of antibodies and histocompatibility antigens. It is the purpose of this project to study the chemistry and structure of antibodies and mouse and human histocompatibility antigens. Antibodies of different specificities and allotype are purified and affinity labeled of the binding site. The chemical sequence of both the light and heavy chains is obtained in order to gain some insight into the nature of antibody specificity and the generation of diversity. Improvements in the isolation methods of histocompatibility antigens are currently being pursued. The characterization of the chemical structure of these proteins is being approached by micro methods and the relationship of the amino acid sequence to immunoglobulin structure is being analyzed.